Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F136/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F136/02—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F136/04—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
  • C08F136/08—Isoprene

Definitions

• the disclosure relates to a polymerization catalyst composition, a method for producing a synthetic polyisoprene using the polymerization catalyst composition, and a synthetic polyisoprene produced by the method.
• a polymerization catalyst composition includes:
• the use of the polymerization catalyst composition enables synthesis of high molecular weight polyisoprene under industrial conditions.
• the use of the polymerization catalyst composition also enables obtainment of a rubber composition that exhibits good durability even under high severity conditions.
• rare earth element means a lanthanoid element, scandium, or yttrium.
• a method for producing a synthetic polyisoprene includes polymerizing an isoprene monomer in the presence of a polymerization catalyst composition including:
• synthetic polyisoprene means an isoprene homopolymer generated by polymerizing (synthesizing) isoprene as a monomer, and includes a polymer whose polymer chain has been partially modified.
• a polymer produced using the disclosed polymerization catalyst composition is synthetic polyisoprene.
• the cis-1,4 bond content of the synthetic polyisoprene is not particularly limited, and may be selected as appropriate according to the purpose.
• the cis-1,4 bond content is preferably 95% or more, more preferably 97% or more, and even more preferably 98% or more.
• the cis-1,4 bond content is 95% or more, the orientation of the polymer chain is good, and sufficient elongational crystallinity can be generated.
• the cis-1,4 bond content is 98% or more, sufficient elongational crystallinity to attain higher durability can be generated.
• the trans-1,4 bond content of the synthetic polyisoprene is not particularly limited, and may be selected as appropriate according to the purpose.
• the trans-1,4 bond content is preferably less than 5%, more preferably less than 3%, and even more preferably less than 2%.
• the 3,4-vinyl bond content of the synthetic polyisoprene is not particularly limited, and may be selected as appropriate according to the purpose.
• the 3,4-vinyl bond content is preferably 5% or less, more preferably 3% or less, and even more preferably 2% or less.
• the weight average molecular weight (Mw) of the polyisoprene is preferably 1,000,000 or more, and more preferably 1,500,000 or more.
• the number average molecular weight (Mn) of the polyisoprene is preferably 400,000 or more, and more preferably 500,000 or more.
• the residual catalyst content of the polyisoprene is preferably 600 ppm or less, and more preferably 200 ppm or less. When the residual catalyst content is 600 ppm or less, the durability under high severity conditions is better.
• the residual catalyst content specifically means the measured value of the rare earth element compound remaining in the polyisoprene.
• the synthetic polyisoprene producing method includes at least a polymerization step, and further includes a coupling step, a cleaning step, and other steps selected as appropriate according to need.
• the polymerization step is a step of polymerizing an isoprene monomer.
• isoprene as a monomer can be polymerized in the same way as a typical polymer producing method using a coordinated ionic polymerization catalyst, except that the disclosed polymerization catalyst composition is used.
• the polymerization catalyst composition used here will be described in detail later.
• Any polymerization method such as solution polymerization, suspension polymerization, liquid phase bulk polymerization, emulsion polymerization, vapor phase polymerization, or solid phase polymerization, may be used.
• any solvent inactive in the polymerization reaction may be used. Examples of such a solvent include n-hexane, toluene, cyclohexane, and a mixture thereof.
• the use of cyclohexane, n-hexane, or a mixture thereof is preferable especially in terms of environmental load, cost, and the like.
• the use of cyclohexane is further preferable for its advantages such as a lower boiling point than that of toluene and low toxicity.
• the components of the polymerization catalyst composition may be separately provided in a polymerization reaction system that includes isoprene as a monomer, to form the polymerization catalyst composition in the reaction system, or (2) the polymerization catalyst composition prepared beforehand may be provided in the polymerization reaction system.
• polymerization may be stopped using a polymerization terminator such as methanol, ethanol, or isopropanol.
• a polymerization terminator such as methanol, ethanol, or isopropanol.
• the polymerization reaction of isoprene is preferably performed under an atmosphere of inert gas.
• the inert gas is preferably nitrogen gas or argon gas.
• the polymerization temperature of the polymerization reaction is not particularly limited.
• the polymerization temperature is preferably in the range of, for example, -100°C to 200°C, and may be approximately the ambient temperature. Note that the cis-1,4 selectivity of the polymerization reaction might decrease if the polymerization temperature is increased.
• the pressure of the polymerization reaction is preferably in the range of 0.1 MPa to 10.0 MPa, to take sufficient isoprene into the polymerization reaction system.
• the reaction time of the polymerization reaction is not particularly limited. The reaction time is preferably in the range of, for example, 1 second to 10 days, though the reaction time may be selected as appropriate according to conditions such as the catalyst type and the polymerization temperature.
• the catalytic activity of the polymerization catalyst composition is preferably 30 kg/mol ⁇ h or more, and more preferably 1000 kg/mol ⁇ h or more. When the catalytic activity is 30 kg/mol ⁇ h or more, polyisoprene can be synthesized more efficiently.
• the value of the catalytic activity mentioned here indicates the ability to produce a polyisoprene per unit mole of catalyst and unit time.
• the polymerization catalyst composition includes at least:
• the component (A) includes a reaction product of a rare earth element compound and a Lewis base without a bond between a rare earth element and carbon.
• the polymerization catalyst composition may further include a compound (component (D)) capable of being an anionic ligand.
• the amide group represented by NQ may be any of: an aliphatic amide group such as a dimethylamide group, a diethylamide group, or a diisopropylamide group; an arylamide group such as a phenylamide group, a 2,6-di-tert-butylphenylamide group, a 2,6-diisopropylphenylamide group, a 2,6-dineopentylphenylamide group, a 2-tert-butyl-6-isopropylphenylamide group, a 2-tert-butyl-6- neopentylphenylamide group, a 2-isopropyl-6-neopentylphenylamide group, or a 2,4,6-tert-butylphenylamide group; and a bistrialkylsilylamide group such as a bistrimethylsilylamide group. Of these, a bistrimethylsilylamide group is
• the molar quantity of the component (A) included in the polymerization catalyst composition is preferably 1/5000 or less and more preferably 1/10000 or less that of the isoprene monomer added subsequently.
• the concentration is preferably in the range of 0.1 mol/l to 0.0001 mol/1.
• the component (A) used in the polymerization catalyst composition is a rare earth element compound or a reaction product of a rare earth element compound and a Lewis base.
• the rare earth element compound or the reaction product of the rare earth element compound and the Lewis base preferably does not have a bond between a rare earth element and carbon.
• the rare earth element compound or the reaction product does not have a rare earth element-carbon bond, the compound is stable and easy to handle.
• the "rare earth element compound” is a compound containing a lanthanoid element composed of any of the elements with atomic numbers 57 to 71 in the periodic table, scandium, or yttrium.
• the lanthanoid element include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.
• the component (A) may be a single kind, or a combination of two or more kinds.
• examples of the Lewis base that reacts with the rare earth element compound include tetrahydrofuran, diethylether, dimethylaniline, trimethylphosphine, lithium chloride, neutral olefins, and neutral diolefins.
• the component (B) used in the polymerization catalyst composition is a hydrocarbyl aluminoxane compound having a hydrocarbon group with a carbon number of 1 to 20.
• the hydrocarbyl aluminoxane compound is preferably alkylaluminoxane.
• alkylaluminoxane examples include methylaluminoxane (MAO) and modified methylaluminoxane.
• modified methylaluminoxane examples include P-MAO and MMAO-3A (made by Tosoh Finechem Corporation).
• the content of the component (B) in the polymerization catalyst composition is preferably 10 times or more in mole with respect to the component (A).
• X organometallic compound represented by the following general formula (X
• the component (C) is preferably an organoaluminum compound represented by the following general formula (Xa): AlR 1 R 2 R 3 ... (Xa) (where R 1 and R 2 are the same or different and are hydrocarbon groups with a carbon number of 1 to 10 or hydrogen atoms, and R 3 is a hydrocarbon group with a carbon number of 1 to 10 and may be the same as or different from R 1 or R 2 ).
• organoaluminum compound having the general formula (Xa) examples include: trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-t-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, and trioctylaluminum; diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, and diisooctylaluminum hydride; and ethylaluminum dihydride, n-propylaluminum
• the organoaluminum compound as the component (C) mentioned above may be a single kind, or a combination of two or more kinds.
• the content of the component (C) in the polymerization catalyst composition is preferably 10 times or more and more preferably 20 to 1000 times in mole with respect to the component (A).
• the content of the component (C) is preferably 1/5000 or more and more preferably 1/3000 to 1/10 the molar quantity of the isoprene monomer added subsequently.
• the compound (component (D)) capable of being an anionic ligand is not particularly limited as long as it is exchangeable with the amide group of the component (A), but preferably has at least one of a OH group, a NH group, and a SH group.
• the compound having a OH group is, for example, aliphatic alcohol or aromatic alcohol.
• Specific examples include dibutylhydroxytoluene, alkylated phenol, 4,4'-thiobis-(6-t-butyl-3-methylphenol), 4,4'-butylidenebis-(6-t-butyl-3-methylphenol), 2,2'-methylenebis-(4-methyl-6-t-butylphenol), 2,2'-methylenebis-(4-ethyl-6-t-butylphenol), 2,6-di-t-4-ethylphenol, 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane,
• hindered phenol-based compound examples include triethyleneglycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythryl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-d
• Examples of a hydrazine-based compound include N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine.
• the compound having a NH group is, for example, a primary amine or secondary amine of alkylamine or arylamine. Specific examples include dimethylamine, diethylamine, pyrrole, ethanolamine, diethanolamine, dicyclohexylamine, N,N'-dibenzylethylenediamine, and bis(2-diphenylphosphinophenyl)amine.
• the compound having a SH group is, for example, aliphatic thiol, aromatic thiol, or any of the compounds represented by the following general formulas (I) and (II): (where R 1 , R 2 and R 3 are each independently represented by -O-C j H 2j+1 , -(O-C k H 2k -) a -O-C m H 2m+1 , or -C n H 2n+1 with at least one of R 1 , R 2 and R 3 being -(O-C k H 2k -) a -O-C m H 2m+1 , j, m and n are each independently 0 to 12, k and a are each independently 1 to 12, and R 4 is a linear, branched, or cyclic, saturated or unsaturated alkylene group, cycloalkylene group, cycloalkylalkylene group, cycloalkenylalkylene group, alkenylene group, cycloal
• Specific examples of the compound represented by the general formula (I) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, (mercaptomethyl)dimethylmethoxysilane, (mercaptomethyl)dimethylethoxysilane, and mercaptomethyltrimethoxysilane.
• R 5 and R 6 are each independently -M-C r H 2r -(where M is -O- or -CH 2 -, and r is 1 to 20)
• R 7 is -O-C j H 2j+1 , -(O-C k H 2k -) a -O-C m H 2m+1 , or -C n H 2n+1 , j, m and n are each independently 0 to 12, k and a are each independently 1 to 12, and R 4 is a linear, branched, or cyclic, saturated or unsaturated alkylene group, cycloalkylene group, cycloalkylalkylene group, cycloalkenylalkylene
• Specific examples of the compound represented by the general formula (II) include 3-mercaptopropyl(ethoxy)-1,3-dioxa-6-methylaza-2-silacyclooctane, 3-mercaptopropyl(ethoxy)-1,3-dioxa-6-butylaza-2-silacyclooctane, and 3-mercaptopropyl(ethoxy)-1,3-dioxa-6-dodecylaza-2-silacyclooctane.
• the component (D) is preferably an anionic tridentate ligand precursor represented by the following general formula (ii): E 1 -T 1 -X-T 2 -E 2 - (ii) (where X is an anionic electron donating group including a coordinating atom selected from atoms of group 15 in the periodic table, E 1 and E 2 are each independently a neutral electron donating group including a coordinating atom selected from atoms of groups 15 and 16 in the periodic table, and T 1 and T 2 are each independently a crosslinking group for crosslinking X with E 1 and E 2 ).
• X is an anionic electron donating group including a coordinating atom selected from atoms of group 15 in the periodic table
• E 1 and E 2 are each independently a neutral electron donating group including a coordinating atom selected from atoms of groups 15 and 16 in the periodic table
• T 1 and T 2 are each independently a crosslinking group for crosslinking X with E 1 and E 2 ).
• the additive amount of the component (D) is preferably 0.01 mol to 10 mol and more preferably 0.1 mol to 1.2 mol, with respect to 1 mol the rare earth element compound (component (A)).
• the additive amount is 0.1 mol or more, the catalytic activity is sufficiently high, so that polyisoprene can be synthesized efficiently.
• the additive amount is preferably equivalent (1.0 mol) to the rare earth element compound, the component (D) may be added excessively.
• the additive amount exceeding 1.2 mol is, however, not preferable because of significant reagent loss.
• the neutral electron donating groups E 1 and E 2 are each a group including a coordinating atom selected from groups 15 and 16.
• E 1 and E 2 may be the same group or different groups.
• Examples of the coordinating atom include nitrogen N, phosphorus P, oxygen O, and sulfur S.
• the coordinating atom is preferably P.
• examples of the neutral electron donating groups E 1 and E 2 include: 1) a diarylphosphino group such as a diphenylphosphino group or a ditolylphosphino group; 2) a dialkylphosphino group such as a dimethylphosphino group or a diethylphosphino group; and 3) an alkylarylphosphino group such as a methylphenylphosphino group.
• a preferable example is a diarylphosphino group.
• examples of the neutral electron donating groups E 1 and E 2 include: 1) a dialkylamino group such as a dimethylamino group, a diethylamino group, or a bis(trimethylsilyl)amino group; 2) a diarylamino group such as a diphenylamino group; and 3) an alkylarylamino group such as a methylphenyl group.
• examples of the neutral electron donating groups E 1 and E 2 include: 1) an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group; and 2) an aryloxy group such as a phenoxy group or a 2,6-dimethylphenoxy group.
• examples of the neutral electron donating groups E 1 and E 2 include: 1) an alkylthio group such as a methylthio group, an ethylthio group, a propylthio group, or a butylthio group; and 2) an arylthio group such as a phenylthio group or a tolylthio group.
• the anionic electron donating group X is a group including a coordinating atom selected from group 15.
• the coordinating atom is preferably phosphorus P or nitrogen N, and more preferably N.
• the crosslinking groups T 1 and T 2 are any groups capable of crosslinking X with E 1 and E 2 . Examples include an arylene group that may have a substituent on an aryl ring. T 1 and T 2 may be the same group or different groups.
• the arylene group may be a phenylene group, a naphthylene group, a pyridylene group, a thienylene group, or the like (preferably a phenylene group or a naphthylene group).
• Any group may be a substituent on an aryl ring of the arylene group. Examples of the substituent include an alkyl group such as a methyl group or an ethyl group, an aryl group such as a phenyl group or a tolyl group, a halogen group such as fluoro, chloro, or bromo, and a silyl group such as a trimethylsilyl group.
• a more preferable example of the arylene group is a 1,2-phenylene group.
• a preferable example of the anionic tridentate ligand precursor represented by the general formula (ii) is represented by the following general formula (iii). This can be, for example, produced by the method described in the following Examples or with reference to Organometallics, 23, p. 4778-4787 (2004 ) or the like. (where R is an alkyl group or an aryl group, and Y is hydrogen, an alkyl group, a halogeno group, a silyl group, or the like).
• a PNP ligand such as bis(2-diphenylphosphinophenyl)amine may be used.
• the synthetic polyisoprene can be used in a rubber composition.
• the rubber composition includes at least the synthetic polyisoprene produced by the disclosed producing method, further includes a rubber component according to need, and further includes other components including a filler such as carbon black, silica, or an inorganic filler and a crosslinker according to need.
• the amount (content) of the synthetic polyisoprene in the rubber component is not particularly limited and may be selected as appropriate according to the purpose.
• the amount is preferably 15 mass% to 100 mass%.
• the synthetic polyisoprene in the rubber component When the amount of the synthetic polyisoprene in the rubber component is 15 mass% or more, the synthetic polyisoprene produces sufficient effects.
• the rubber composition or the crosslinked rubber composition can be used in tires. Applying the rubber composition or the crosslinked rubber composition to the tread of the tire is advantageous in terms of durability.
• the rubber composition or the crosslinked rubber composition may be used not only in tires but also in anti-vibration rubber, seismic isolation rubber, belts (conveyor belts), rubber crawlers, various hoses, etc.
• the reactor was then taken out of the glove box, 235.0 g cyclohexane and 70 g isoprene were added, and the polymerization reaction was performed at 25°C for 15 hours. After the polymerization, 1 mL an isopropanol solution with 5 mass% 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) was added to stop the reaction. Further, the polymer was separated using a large amount of methanol and vacuum-dried at 70°C, to obtain a synthetic polyisoprene A. The yield of the obtained synthetic polyisoprene A was 60 g.
• Example 2 The same method as in Example 1 was used except that the polymerization was performed at 50°C for 2 hours. As a result, a synthetic polyisoprene B was obtained with a yield of 65 g.
• a magnetic stirrer was put in a flask (100 mL), and isoprene (2.04 g, 30.0 mmol) and a chlorobenzene solution (16 mL) of [Y(CH 2 C 6 H 4 NMe 2 -O) 2 (PNP)] (12.5 ⁇ mol) were added. After this, a chlorobenzene solution (4 mL) of [PhMe 2 NH][B(C 6 F 5 ) 4 ] (12.5 ⁇ mol) was added under high-speed stirring. Stirring was performed at the ambient temperature for 5 minutes to cause the reaction, and then methanol was added to end the polymerization.
• the reaction solution was poured into a 200 mL a methanol solution including a small amount of hydrochloric acid and butylhydroxytoluene (stabilizer).
• the precipitated polymer product was isolated by decantation, cleaned with methanol, and dried at 60°C to obtain a polymer Y (yield: 100%).
• the polymerization reaction was performed under the same conditions as test C described in PTL 3, to obtain a polymer Z.
• the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) of the synthetic polyisoprene in terms of polystyrene were determined by gel permeation chromatography [GPC: HLC-8220GPC made by Tosoh Corporation, column: 2 GMH XL columns made by Tosoh Corporation, detector: differential refractometer (RI)] with respect to monodisperse polystyrene. The measurement temperature was 40°C. THF was used as an eluting solvent.
• the rare earth element content (ppm) of the synthetic polyisoprene was determined using a wavelength dispersion type fluorescent X-ray apparatus [XRF-1700 made by Shimadzu Corporation] with respect to polyisoprene whose rare earth element content is known. Rh was used as an X-ray source, and the measurement was conducted under vacuum. [Table 1] Ex. 1 Ex.
• polybutadiene with a high molecular weight and a high cis-1,4 bond content was obtained as a result of polymerizing, using the polymerization catalyst composition including the components (A), (B), and (C), the isoprene monomer so that (the isoprene monomer)/(the component (A)) is 5000 or more, (the component (C))/(the component (A)) is 10 or more, and (the isoprene monomer)/(the component (C)) is 5000 or less.
• the synthetic polyisoprene produced by the disclosed producing method and a rubber composition including the synthetic polyisoprene are suitable for use in, for example, tire members (especially the tread member of the tire).

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